The present invention relates to a laser marker for use in positioning work at construction sites.
A laser marker used in positioning work at construction sites emits laser light serving as a reference line. FIG. 7 shows one example of a conventional laser marker 101. The laser marker 101 includes a stand 102 and a cover 103 rotatably mounted on the stand 102. The cover 103 accommodates therein a laser unit 104. The cover 103 has a window (not shown) through which a laser light passes.
The laser unit 104 has a lens unit 106 including a laser light source. The laser unit also includes a lens 107 adapted for receiving laser light emitted from the lens unit 106 and converting the laser light to a line beam. The line beam (i.e., horizontal line beam or vertical line beam) emitted from the lens 107 are applied outside the cover 103 through the window (not shown), and are utilized in positioning work at a construction site. Such a laser marker is described in laid-open Japanese Patent Application Kokai No. 2004-109509.
The laser marker may be used in a bright place or a dark place. In the bright place, the laser line beam has low contrast because of bright ambient atmosphere. Visibility to the laser line beam may be lowered if intensity of ambient light is high, which may lower the positioning workability. On the other hand, in a dark place, the laser line beam has high contrast and can be clearly seen. However, the laser line beam may glare, inevitably tiring the user's eyes, particularly when the user gazes at the laser beam. In this case also, working efficiency may be lowered.